1. Field of the Invention
The present invention relates to a vehicle lamp having a plurality of lamp units and, more particularly, a vehicle lamp equipped with a swiveling mechanism for changing an illumination direction and an illumination range of a light source in answer to a traveling condition.
2. Background Art
Since an irradiation light emitted from a headlight of a vehicle illuminates a front center portion of the road, the headlight cannot often get hold of enough illumination range in front of a traveling direction during going around a curve, turning to the right or left, changing the lane, or the like. As the vehicle lamp that can satisfactorily get hold of illumination range of the irradiation light during going around a curve, or the like and makes it possible for the driver to get a good view of the road, there is a swivel type vehicle lamp equipped with a swiveling mechanism that turns the lamp unit to the left and right (see Patent Documents 1 and 2, for example).
[Patent Document 1] JP-A-2006-117164
[Patent Document 2] JP-A-2006-179246
The swivel-type vehicle lamp is constructed such that the lamp unit is supported to a frame member, which is supported to the lamp body, via the swiveling mechanism to turn leftward and rightward. The lamp unit and the swiveling mechanism are respectively controlled by a control unit in response to a traveling condition of the vehicle. Thus, a direction of the illumination light emitted from the lamp unit can be changed leftward and rightward by turning the lamp unit on the frame member, in response to the traveling condition of the vehicle. As a result, the illumination range of the irradiation light can be ensured ahead of the turning direction even during going around a curve, or the like, and the driver can make sure of a good side visibility during turning the vehicle.
However, in the swivel-type vehicle lamp in the conventional art, a plurality of lamp units are supported by the frame member to turn to the right and left, and the lamp units are integrally turned on the frame member in response to the traveling condition of the vehicle. Therefore, the illumination range is merely increased according to an angle at which the lamp units are turned to the right and left, and thus such vehicle lamp can respond only to the curved road whose turning radius is relatively large and which does not need the wide illumination range so much.
For this reason, an effective situation of such vehicle lamp is restricted to a sinuous road in, for example, a mountainous region, a lane change, and the like. Accordingly, the enough illumination range cannot be ensured ahead of the turning direction of the vehicle during a left or right turn at an intersection, and the like. As a result, it is considered that the effect of the swivel system cannot be sufficiently achieved.
In addition, when an turning angle of all of a plurality of lamp units is increased to ensure the enough illumination range ahead of the turning direction of the vehicle, the illumination range on the opposite side to the turning direction of the vehicle would be decreased so that a forward visibility may be lowered. In contrast, there is such a system that a plurality of lamp units are driven by respectively using a plurality of actuators (driving units). However, in this system, an overall lighting equipment may be increased in size and becomes expensive.
For this reason, the vehicle lamp that can realize a flexible light distribution change such as a swiveling of the overall light distribution by a single actuator, while adequately maintaining a position of the hot zone (high luminous intensity area) is demanded.